The invention relates to a method for the production of a wear resistant part of a soil working tool, the wear resistant part essentially consisting of an iron matrix having hard particles embedded therein.
The term wear resistant part means herein a part of a soil working tool which is in contact with the soil to be worked, and which consequently is subject to wear. Typical wear resistant parts are plough shares, harrow tooth tips, discs for disk harrows, blades for rotary cultivators, and seed spouts for seeding machines.
It is well known to produce wear resistant parts by melting and subsequently casting carbon containing iron under such conditions that the carbon is separated in the form of free iron carbide particles. The material thus produced, white cast iron, has a very high hardness and resistance to wear.
Likewise, it is well known to produce wear resistant parts by melting and subsequently rolling an iron alloy.
European patent application No. 0 046 209 A1 discloses wear resistant parts comprising 30-80% by weight of a carbide material and 20-70% by weight of a matrix material selected from the group consisting of steel, steel and iron, steel and copper, and steel and nickel, carbide material being embedded in and bonded to matrix. The wear resistant parts are prepared by subjecting a mixture of hard carbide particles and metal powder to a cold isostatic compaction to form a compacted preform. The compacted preform is then sintered at a temperature of about 1050.degree. C. for about 1 hour and subsequently the sintered body is isostatically pressed at a temperature of about 1230.degree. C. for about 1 hour at a pressure of above 700 kg/cm.sup.2, and preferably about 1050 kg/cm.sup.2, under a protective atmosphere. These operations are time consuming and the use of a high temperature at a high pressure and under a protective atmosphere requires a complicated equipment.
Furthermore it is well known, cf. R. C. D. Richardson: The Wear of Metallic Materials by Soil--Practical Phenomena, J. agric. Engng Res. (1967) 12 (1), 22-39, that the particle size distribution of the hard particles in a matrix of the type specified above is an important parameter of the wear resistance of wear resistant parts of soil working tools, and that optimum wear resistance is obtained by adapting the particle size distribution of the hard particles to the soil type to be worked.
With the known methods for the production of wear resistant parts it is practically impossible to obtain a predetermined particle size distribution in the finished wear resistant part.
The object of the invention is to provide a simple method of the type defined above which does not suffer from this drawback.